If you want to bring them into Microsoft paint ( comes standard on all PC's runnig windows) Go to start, Programs, accessories, PAINT.

Open up the picture in there. Once it's open in paint, go to the tab IMAGE and then down the list to ATTRIBUTES. You'll see a width and height column. Change those numbers to something around 800 or below and then save out the image.

Take note that this only works on .JPG .GIF and .BMP images. If your trying to resize a .TIFF image you will have to use a different program.

Most imaging programs have some sort of resizing feature in them. If you tell me what program your currently using I'll give you a detailed explaination of how to resize in your specific program.